1. Field of Invention
The invention relates generally to a low power driver, and more specifically to apparatuses and methods for programming the output impedance of the driver.
2. Art Background
Integrated circuits (IC) contain drivers which are used to transmit clock and data signals over transmission lines, such as an internal trace of an IC. The output impedance of the driver needs to match the impedance of the transmission line to which the driver is attached. The application dependant nature of IC design requires different impedances for a given trace line within an IC. The impedance of a given trace line can change with the application of the IC. The impedance of the driver must match the impedance of the trace line. From an IC manufacturing perspective it is desirable to use a single driver design for a number of different IC applications. To this end, off chip resistors have been used to adjust the output impedance of the driver to the specific impedance presented by the trace line. This solution is time and material intensive, resulting in increased cost to the IC manufacturer. This presents a problem.
An approach which avoids off chip resistors requires a specific IC chip for each output impedance of interest. This approach is also expensive requiring a large inventory of different chips which are costly to produce. This presents a problem.